The present invention relates generally to laser cutting and welding systems and more particularly to methods of bonding materials together using a laser, and in particular as those methods relate to the production social expression products such as of greeting cards.
Multi-layered products, known as composites, typically have a substrate and at least one layer of material bonded to the substrate. Composites are used for a variety of purposes and in a variety of industries. Social expression products such as gift wrap, stationary, knick knacks, calendars and greeting card often have decorative lettering or designs bonded to substrate. In the case of greeting cards, the substrate is typically a paper card stock. Currently, the process for creating composites requires applying adhesive to the layer of material and applying physical pressure and heat to activate the adhesive to bond the layer to the substrate.
The application of a layer of shiny script to a greeting card substrate, for example, involves the use of two metal plates or xe2x80x9cdies,xe2x80x9d in which one die has a positive image of the script engraved on it and the other a negative image. The card substrate is then placed flatly between the dies. A sheet of film, also known as a xe2x80x9ccarrier,xe2x80x9d having a layer of aluminum foil attached to it on one side and a layer of adhesive applied to the aluminum foil, is then placed on the substrate. Under intense heat and pressure, the sheet of film and the substrate are crushed together between the dies, thereby activating the adhesive and imprinting the aluminum foil onto the card substrate in the pattern of the script. The film carrier is then removed from the substrate, leaving only the aluminum foil script bonded to the substrate.
Traditional heat/pressure-based methods for creating composites have several disadvantages that are apparent from the greeting card process described above. First, the creation of the positive and negative dies is very time consuming and labor intensive. Second, because the top layer of material and the substrate are crushed together, the aluminum is forced to assume the texture of the card, making the process very stock sensitive. Finally, the resulting script or image has a ragged look around the edges, which may not be the aesthetic effect desired. Thus, it can be seen that there is a need for an improved method of bonding a layer of material to a substrate such as to bond foil to a greeting card.
In accordance with this need, a method of bonding a layer to a substrate is provided. According to one embodiment of the method, the layer is placed on the substrate and a laser beam is directed onto the layer to activate an adhesive disposed between the layer and the substrate to bond the layer to the substrate. An excess portion of the layer being lased may be cut away while the trace profile is being traced by the laser beam.
The layer may be placed on the substrate without adhesive, and a laser beam may be directed onto the layer in a closed path to bond the layer to the substrate and cause the layer to puff away from the substrate within the closed path. Alternatively, the substrate may be placed on the layer, and a laser beam directed onto the substrate to activate an adhesive disposed between the layer and the substrate to bond the layer to the substrate.
The laser beam may be moved along a path represented by a trace profile. The trace profile may be comprised of a plurality of vectors defining a path on the layer. Commands within the trace profile may be grouped according to the portion of the path they represent. Beam profiles may be used to configure the beam, and a trace profile may use one or more beam profiles to create an image. The commands within the trace profile may be grouped according to the beam profiles being used.
The laser beam may be moved along a closed path to puff the layer away from the substrate within the closed path. Moving the laser beam repeatedly over the closed path may further puff the layer away from the substrate within the closed path. A portion of the layer outside of the closed path may be lased to bond the layer to the substrate such that the outside portion is flatter than the portion of the layer inside the closed path.
The heat of the laser beam may be controlled to (1) increase or decrease the thickness of a bonded region along which the layer and the substrate are bonded, and (2) to change the color of the layer. The pulse width of the laser beam may be changed to increase or decrease the distance between successive portions of a bonded region along which the layer and the substrate are bonded.
A composite is also provided in accordance with the foregoing needs. The composite is comprised of a substrate, a layer bonded to the substrate along a closed path, and a material disposed between the layer and the substrate within the closed path. The material puffs the layer away from the substrate in response to a laser beam. The material may be a gas or vapor released from the layer, or the substrate.
The layer may be bonded to the substrate with an adhesive, and the material may be a gas or vapor released from the adhesive. The layer may be also melted to the substrate along the enclosed path without an adhesive. The substrate may be comprised of many different materials, including, but not limited to polyester, vinyl, polystyrene, ethylene vinyl acetate, polypropylene, aluminum, cloth, wood, veneer, plastic, leather, glass, paper, parchment, textured stock, vellum, textiles, a film carrier having an aluminum deposit or any combination thereof.
A method of bonding a layer of thermoplastic material to a paper substrate is also provided in accordance with the foregoing needs. According to the method the thermoplastic layer is placed on the substrate, and the laser beam is directed onto it to melt a local area of the thermoplastic, thereby bonding the layer to the paper substrate.
A method of decorating a greeting card is also provided in accordance with the foregoing needs. According to the method, a layer of decorative material is placed on a greeting card stock, and a laser beam is directed onto the layer to activate an adhesive disposed between the layer and the card stock to bond the layer to the greeting card stock.